1. Field of the Invention
The present invention relates to a sealant dispensing method of a liquid crystal display (LCD) device, and more particularly, to a sealant dispensing method of an LCD device by a liquid crystal dispensing method.
2. Discussion of the Related Art
Among various ultra-thin flat type display devices, which include a display screen having a thickness of several centimeters, a liquid crystal display (LCD) device can be widely used for notebook computers, monitors, aircraft, and etc. since it has advantages of low power consumption and portability.
The LCD device is manufactured by steps of preparing a lower substrate having a thin film transistor and a pixel electrode on a transparent substrate; preparing an upper substrate having a black matrix layer, a color filter layer, and a common electrode on a transparent substrate; and forming a liquid crystal layer between the lower and upper substrates.
At this time, the method for forming the liquid crystal layer between the lower and upper substrates is classified into a liquid crystal injection method and a liquid crystal dispensing method.
In the liquid crystal injection method, a sealant is dispensed in a pattern having an inlet on any one of lower and upper substrates, and the lower and upper substrates are bonded to each other. Then, liquid crystal is injected to a space between the lower and upper substrates through the inlet of the sealant.
In the liquid crystal dispensing method, a sealant is dispensed in a pattern having no inlet on the lower substrate, and liquid crystal is dispensed on the lower substrate. Then, the lower and upper substrates are bonded to each other.
In case of the liquid crystal injection method, it may take a long time to inject the liquid crystal into the space between the lower and upper substrates, thereby decreasing the production yield. For example, if manufacturing a large-sized LCD device by the liquid crystal injection method, it takes a long time for injection of liquid crystal. To this end, the manufacturer of large-sized LCD devices has become generally performed using the liquid crystal dispensing method.
The method for dispensing the sealant of the pattern having no inlet by the liquid crystal dispensing method is classified into a screen printing method and a dispensing method using a dispenser. If applying the screen printing method, the screen may come into contact with a substrate, whereby it may damage an alignment layer of the substrate. In this respect, the dispensing method is used generally.
Hereinafter, a related art dispensing method will be explained with reference to the accompanying drawings.
FIG. 1 is a schematic view of a sealant dispensing method using a dispenser according to the related art.
First, as illustrated in FIG. 1, the related art dispenser is provided with a syringe 10 and a nozzle 20.
The syringe 10 has a sealant 15 therein. The nozzle 20 is connected to a lower end of the syringe 10 to supply the sealant 15 to a substrate 1.
The dispenser moves along a direction (as indicated by the arrow in the figure) from a starting point (s) of the substrate 1, and then returns to the starting point (s) of the substrate 1, forming a closed sealant path. As the dispenser moves along the substrate, the sealant 15 is discharged to the substrate 1 through the nozzle 20. Accordingly, the sealant 15 of the pattern having no inlet is dispensed to the substrate 1.
However, the related art sealant dispensing method has the following disadvantages.
First, because the sealant 15 has a particular viscosity, the sealant 15 may coagulate in the end of the nozzle 20 of the dispenser. Thereafter, when the sealant material is supplied to the starting point (s) of the substrate 1 through the nozzle 30, the coagulated sealant is discharged to the starting point (s) of the substrate 1. In addition, because the dispenser moves along the arrow direction from the starting point (s) of the substrate 1, and then turns back to the starting point (s) of the substrate 1, the coagulated sealant 15 may be excessively dispensed to the starting point (s) of the substrate 1. In this case, when bonding the two substrates to each other, the sealant 15 spreads to the inside of the substrate 1 in which the liquid crystal is formed. Thus, the liquid crystal dispensed on the substrate 1 may be contaminated due to the spread of sealant.
Second, to prevent the sealant 15 from being coagulated at the starting point (s), the dispenser may be stopped before the starting point (s). In this case, the sealant 15 can be disconnected. That is, the liquid crystal flows to the outside through the portion of the sealant.